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  <script>
    let arr = [88, 20, 10, 100, 50]
    let re = 0
    for (let i = 0; i < arr.length; i++) {
      if (arr[i] === 10) {
        // re=i是输出10的索引位置
        re = i
        break
      }
    }
    document.write(re)
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